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3.4.5. Windowing Functions

💡 First Principle: Windowing functions divide continuous streams into finite chunks for aggregation—because you can't summarize infinity. Different window types serve different analytical needs: counting events per hour, calculating rolling averages, or grouping activity sessions.

Scenario: You need to: (1) Count events every 5 minutes (tumbling), (2) Calculate rolling average over overlapping intervals (hopping), (3) Group events until no activity for 30 seconds (session).

Window Types

Window TypeBehaviorUse Case
TumblingFixed, non-overlapping intervalsHourly counts, daily summaries
HoppingFixed intervals with overlapRolling averages
SlidingEvent-triggered, fixed lengthPer-event rolling calculations
SessionGap-based groupingUser activity sessions
Visual: Window Types
Alvin Varughese
Written byAlvin Varughese
Founder•15 professional certifications